astatine and Carcinoma--Squamous-Cell

The monoclonal antibody cetuximab, targeting the epidermal growth factor receptor (EGFR), is a promising molecular targeting agent to be used in combination with radiation for anticancer therapy. In this study, effects of cetuximab in combination with alpha-emitting radioimmunotherapy (RIT) in a panel of cultured human squamous cell carcinomas (SCCs) were assessed.. SCC cell lines were characterized and treated with cetuximab in combination with anti-CD44v6 RIT using the astatinated chimeric monoclonal antibody U36 ((211)At-cMAb U36). Effects on (211)At-cMAb U36 uptake, internalization and cell proliferation were then assessed in SCC cells.. Cetuximab in combination with (211)At-cMAb U36 mediated increased growth inhibition compared to RIT or cetuximab alone in two cell lines. However, cetuximab also mediated radioprotective effects compared to RIT alone in two cell lines. The radioprotective effects occurred in the cell lines in which cetuximab clearly inhibited cell growth during radiation exposure. Cetuximab treatment also influenced (211)At-cMAb-U36 uptake and internalization, suggesting interactions between CD44v6 and EGFR.. Results from this study demonstrate the vast importance of further clarifying the mechanisms of cetuximab and radiation response, and the relationship between EGFR and suitable RIT targets. This is important not only in order to avoid potential radioprotective effects, but also in order to find and utilize potential synergistic effects from these combinations.

Topics: Alpha Particles; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Astatine; Biological Transport; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cetuximab; Humans; Radioimmunotherapy; Tumor Stem Cell Assay

To generate and evaluate a modular recombinant transporter (MRT) for targeting 211 At to cancer cells overexpressing the epidermal growth factor receptor (EGFR).. The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[211 At]astato-5-guanidinomethylbenzoate (SAGMB), its 125 I analogue SGMIB, or with 131 I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines.. The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 10-20 times more cytotoxic than [211 At]astatide for all three cell lines.. The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted alpha-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this 211 At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

Topics: Alpha Particles; Antigens, Polyomavirus Transforming; Astatine; Benzoates; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Nucleus; Confidence Intervals; Dihydropteridine Reductase; Diphtheria Toxin; Drug Carriers; Endosomes; Epidermal Growth Factor; ErbB Receptors; Escherichia coli Proteins; Glioblastoma; Guanidine; Guanidines; Hemeproteins; Humans; NADH, NADPH Oxidoreductases; Radioimmunotherapy

The aim of the present study was to investigate if treatment with lysosomotropic weak bases could increase the intracellular retention of radiohalogens and thereby increase the therapeutic effect of radionuclide tumor targeting.. Four different lysosomotropic bases, chloroquine, ammonium chloride, amantadine, and thioridazine, were investigated for their ability to increase radiohalogen retention in vitro. The two most promising substances, chloroquine and ammonium chloride, were studied in several cell lines (A431, U343MGaCl2:6, SKOV-3, and SKBR-3) in combination with radiolabeled epidermal growth factor (EGF) or the HER2 binding affibody (Z(HER2:4))(2).. The uptake and retention of radionuclides was found to be substantially increased by simultaneous treatment with the lysosomotropic bases. The effect was, however, more pronounced in the epidermal growth factor:epidermal growth factor receptor (EGF:EGFR) system than in the (Z(HER2:4))(2):HER2 system. The therapeutic effect of ammonium chloride treatment combined with (211)At-EGF was also studied. The effect obtained after combined treatment was found to be much better than after (211)At-EGF treatment alone.. The encouraging results from the present study indicate that the use of lysosomotropic weak bases is a promising approach for increasing the therapeutic effect of radionuclide targeting with radiohalogens.

Topics: Amantadine; Ammonium Chloride; Antimalarials; Antipsychotic Agents; Antiviral Agents; Astatine; Carcinoma, Squamous Cell; Cell Line, Tumor; Chloroquine; Epidermal Growth Factor; Glioma; Humans; Iodine Radioisotopes; Radioimmunotherapy; Radioisotopes; Recombinant Fusion Proteins; Thioridazine

In advanced head and neck squamous cell carcinoma (HNSCC), there is a need for an adjuvant treatment. We aim to evaluate the biodistribution and therapeutic effect of radioimmunotherapy using the alpha emitting, astatine-211-labeled, chimeric monoclonal antibody U36 (U36) on the HNSCC cell line UT-SCC7 in vivo.. Xenograft tumors were inoculated subcutaneously in nude mice. Astatine-211-labeled U36 was injected intravenously with or without blocking of target with nonlabeled U36.. In the biodistribution experiments, radioactivity was measured in tumors and various organs at set time points. In the therapeutic experiments, two groups (with or without blocking) received therapy, and the tumor growth was compared with that of controls. In addition, one group received nonlabeled U36 only.. The biodistribution experiments demonstrated that astatine-211-labeled U36 could target UT-SCC7 xenografts in nude mice. With time, uptake increased in tumors and decreased in normal organs. Nonlabeled U36 did not influence tumor growth. In the two therapy groups, 18 of 20 tumors responded to therapy by decreasing or stabilizing their volumes. Significant difference was seen between the treated groups and the controls (P < .05).. The study illustrates the specific binding of astatine-211-labeled U36 to HNSCC and suggests radioimmunotherapy with the alpha emitting radionuclide to be a useful treatment modality.

Topics: Animals; Antibodies, Monoclonal; Astatine; Carcinoma, Squamous Cell; Cell Growth Processes; Cell Line, Tumor; Cell Movement; Chimerin Proteins; Disease Models, Animal; Head and Neck Neoplasms; Mice; Mice, Nude; Radioimmunotherapy; Random Allocation; Staining and Labeling

The purpose of this study was to analyse the properties of the astatinated chimeric MAb (cMAb) U36 as a conjugate to selectively target and eradicate head and neck squamous cell carcinoma (HNSCC).. cMAb U36 was labelled with 211At via the linker N-succinimidyl 4-(trimethylstannyl)benzoate (SPMB). The quality of the conjugate was extensively evaluated for binding and internalisation capacity, and compared with 125I-SPMB-cMAb U36. The cellular toxicity of the astatinated conjugate was assessed in two types of in vitro growth assay and compared with 131I-labelled cMAb U36 (directly labelled).. Comparisons between 211At-cMAb U36 and 125I-cMAb U36 demonstrated an optimal functional capacity of the labelled products. Immunoreactivity and affinity assays showed high immunoreactive fractions (>93%), and an affinity in good agreement between the astatinated and iodinated antibodies. For both conjugates, specific binding to HNSCC cells could be demonstrated, as well as some internalisation. Retention of the astatinated conjugate was just slightly lower than for the iodinated conjugate and still reasonable for therapeutic use (31+/-2% vs 42.6+/-1.0% at 22 h), demonstrating no adverse effects from astatination of the antibody. Studies on cellular toxicity demonstrated a dose-dependent and antigen-specific cellular toxicity for 211At-cMAb U36, with about 10% cell survival at 50 decays per cell. The 131I-labelled conjugate was not as efficient, with a surviving cell fraction of about 50% at 55 decays per cell.. These results indicate that 211At-cMAb U36 might be a promising future candidate for eradicating HNSCC micrometastases in vivo.

Topics: Antibodies, Monoclonal; Astatine; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Survival; Drug Evaluation, Preclinical; Feasibility Studies; Head and Neck Neoplasms; Humans; Radioimmunotherapy

The EGFR-TKI (epidermal growth factor receptor tyrosine kinase inhibitor) gefitinib ("Iressa", ZD1839), a reversible growth inhibitor of EGFR-expressing tumour cells, has been shown to enhance the antitumour effect of ionising radiation, and also to increase the uptake of radioiodinated EGF. Thus, combination of gefitinib treatment and radionuclide targeting is an interesting option for therapy of brain tumours that are difficult to treat with conventional methods. The aim of this study was to evaluate how pre-treatment with gefitinib affects binding of astatinated EGF ((211)At-EGF) to cultured glioma U343 cells, which express high levels of EGFR. The growth of U343 cells in the presence of gefitinib was investigated, and it was found that gefitinib does not significantly inhibit the growth of these cells. Nevertheless, the uptake of (211)At-EGF in U343 cells was markedly increased (up to 3.5 times) in cells pre-treated with gefitinib (1 microM). This indicates that a combination of gefitinib treatment and radionuclide targeting to EGFR might be a useful therapeutic modality, even for patients who do not respond to treatment with gefitinib alone.

Topics: Astatine; Carcinoma, Squamous Cell; Cell Division; Cell Line, Tumor; Dose-Response Relationship, Drug; Epidermal Growth Factor; ErbB Receptors; Gefitinib; Glioma; Humans; Metabolic Clearance Rate; Protein-Tyrosine Kinases; Quinazolines; Radioisotopes; Radiopharmaceuticals

The EGFR-TKI (epidermal growth factor receptor tyrosine kinase inhibitor) gefitinib ['Iressa' (trademark of the AstraZeneca group of companies), ZD1839] increases the cellular uptake of radiolabelled epidermal growth factor (EGF). We investigated gefitinib treatment combined with astatine-211 EGF targeting in vitro using two cell lines expressing high levels of EGFR: A431 (sensitive to gefitinib) and U343MGaCl2:1 (resistant to gefitinib). In both cell lines, the uptake of 211At-EGF was markedly increased by concomitant treatment with gefitinib. Survival was investigated using both a clonogenic survival assay and a cell growth assay. Combined gefitinib and 211At-EGF treatment reduced the survival of U343 cells 3.5-fold compared with 211At-EGF alone. In A431 cells, 211At-EGF treatment resulted in very low survival, but combined treatment with gefitinib increased the survival by about 20-fold. These results indicate that combined treatment with gefitinib might increase the effect of ligand-mediated radionuclide therapy in gefitinib-resistant tumours and decrease the effect of such therapy in gefitinib-sensitive tumours.

Topics: Antineoplastic Agents; Astatine; Astrocytoma; Carcinoma, Squamous Cell; Cell Division; Cell Line, Tumor; Cell Survival; Combined Modality Therapy; Epidermal Growth Factor; Gefitinib; Humans; Quinazolines; Radiopharmaceuticals; Treatment Outcome